1. Field of the Invention
The present invention relates to an optical system and more particularly to a single aperture multichannel optical system.
2. Brief Description of Related Art
Optical sensors and detectors, including night vision systems, often use multiple imaging channels, each operating at a specified waveband. Such multiple imaging channels often use either multiple apertures or share a common aperture of an objective piece. However, multiple apertures may have limited boresight retention ability. Further, single aperture multiple imaging channels based optical systems use tilted planar dichoric beam splitters to separate imaging channels, which may introduce a number of optical distortions.
Furthermore, the need for compact visible-light images has led to extensive use of short focal length, small aperture lenses that meet the strict space and weight constraints required for many commercial and military applications. While these miniature refractive lenses often perform well in good lighting and within a small range of optical magnification, resolution and light collection are limited by the small aperture, focal length and physical track length of the lens. One method of significantly increasing focal length and magnification without a corresponding increase in track length consists of reflecting the optical path multiple times with concentric reflectors, thus constraining the optical propagation to occur within a thin optical element. However, with this approach, imaging in disparate spectral bands (for example, visible, laser and near infrared (IR)), seeing a laser designator spot, detecting a laser range finder return, and maximizing use of common elements with disparate sensors to minimize sources of boresight error while optimizing weight and volume can be a challenge.